Unity Platforms Skill

Supported Platforms

Unity 6 supports the following platform categories:

• Desktop: Windows, macOS, Linux
• Mobile: Android, iOS
• Emerging: visionOS, tvOS
• Web: WebGL (including Facebook Instant Games)
• Server: Dedicated Server
• Embedded: Embedded Linux, QNX
• UWP: Universal Windows Platform
• Closed Platforms: PlayStation, Xbox (Game Core), Nintendo (require confidentiality/legal agreements and registration via Platform Module Installation)

Build Profiles and Settings

Build Profiles replace the old Build Settings window. A build profile is a set of configuration settings for building your application on a particular platform.

Two Profile Types

1. Platforms: Display currently installed platforms with shared settings across all configurations. Enabling options like Development Build applies universally. Platforms share identical scene data across profiles.
2. Build Profiles: Independent configurations not shared across platforms. Each can specify unique scenes and settings. Stored as asset files compatible with version control.

Key Features

• Custom naming for organizing multiple build configurations
• Version control integration (profiles stored as asset files)
• Per-profile scene assignment
• Development builds (debug symbols, Profiler access) and release builds
• Access via File > Build Profiles
• Duplicate a platform via right-click > "Copy to new profile"

Scene Management

Scenes are managed per-profile. You can add, exclude, remove, and reorder scenes in your build. Each unique Scene file represents a unique level or screen.

Platform Scripting Defines

Use #if directives to conditionally compile code per platform.

Platform Defines

Feature and Backend Defines

.NET API Level Defines

Version Defines

Format: UNITY_X, UNITY_X_Y, UNITY_X_Y_Z, UNITY_X_Y_OR_NEWER

Example for Unity 6000.0.33:

• UNITY_6000, UNITY_6000_0, UNITY_6000_0_33, UNITY_6000_0_OR_NEWER

Mobile Optimization

iOS

Architecture: ARM64 only (no ARMv7).

Scripting Backend: IL2CPP required for iOS (no Mono option).

Player Settings (Edit > Project Settings > Player > iOS):

• Bundle Identifier: com.CompanyName.ProductName
• Signing Team ID + Automatic Sign for Xcode
• Target minimum iOS version selectable
• Metal API Validation for debug shader issues
• Metal Write-Only Backbuffer for performance in non-default orientations
• Force hard shadows on Metal (point sampling for performance)
• Orientation: Portrait, Landscape, or Auto Rotation with allowed orientations
• Launch Screen: Default, Image, or Custom Storyboard
• Requires ARKit support restricts to iPhone 6s/iOS 11+

Android

Architectures: ARMv7 and ARM64 (ARM64 requires IL2CPP).

Player Settings (Edit > Project Settings > Player > Android):

• Package Name: com.YourCompanyName.YourProductName
• Minimum API Level and Target API Level
• Graphics API: Auto (Vulkan first, GLES fallback), Vulkan, or OpenGL ES 3.x
• Split APKs by target architecture for smaller downloads on Google Play
• Keystore configuration for signing (custom keystore for production)
• Scripting Backend: Mono or IL2CPP
• API Compatibility: .NET Framework or .NET Standard 2.1
• Managed Stripping Level: Minimal to High

Key Difference: Android hardware capabilities vary significantly between models. Test across multiple devices.

Mobile Optimization Tips

• Use ASTC texture compression (supported on both iOS and Android modern devices)
• Minimize draw calls via batching (static and dynamic)
• Use AssetBundles or Addressables for on-demand content
• Profile with Unity Profiler and platform-specific tools
• Reduce shader complexity on mobile GPUs

WebGL Considerations

Memory Management

• Unity heap implemented as WebAssembly Memory (resizable ArrayBuffer)
• Heap can expand up to 4 GB (Maximum Memory Size in Player Settings)
• Asset data unpacked from .data file into virtual memory file system (Emscripten)
• Garbage collector only runs at end of each frame (no mid-frame collection)
• Available memory depends on device, OS, browser (32/64-bit), and tab isolation model

Memory Optimization

Use StringBuilder instead of string concatenation in loops:

// BAD: Creates ~15 GB temporary allocations for 100k iterations
string hugeString = "";
for (int i = 0; i < 100000; i++)
    hugeString += "foo";

// GOOD: Pre-allocated StringBuilder
var sb = new StringBuilder();
for (int i = 0; i < 10000; i++)
    sb.Append("foo");

Use NativeArray<T> for temporary allocations to bypass GC:

using (var data = new NativeArray<byte>(size, Allocator.Temp))
{
    // Memory freed immediately upon scope exit
}

Use AssetBundles for asset loading (downloads directly into Unity heap without extra browser allocation).

Enable Data Caching (IndexedDB/Caching APIs) to reduce re-downloads.

JavaScript Interop

Unity supports two JavaScript plug-in file types:

• .jslib: Define functions callable from C# code
• .jspre: Include existing JavaScript libraries

Limitation: Only ECMAScript 5 (ES5) syntax supported in .jslib and .jspre files. ES6 is not yet supported.

#### .jslib Plugin Example

// Assets/Plugins/WebGL/MyPlugin.jslib
mergeInto(LibraryManager.library, {
    ShowAlert: function (message) {
        window.alert(UTF8ToString(message));
    },
});

#### C# Calling JavaScript

using System.Runtime.InteropServices;
using UnityEngine;

public class WebGLBridge : MonoBehaviour
{
    [DllImport("__Internal")]
    private static extern void ShowAlert(string message);

    void Start()
    {
        #if UNITY_WEBGL && !UNITY_EDITOR
        ShowAlert("Hello from Unity!");
        #endif
    }
}

IL2CPP vs Mono

IL2CPP (Intermediate Language To C++)

IL2CPP is Unity's custom AOT scripting backend that converts C# to native code via C++.

Conversion Pipeline:

1. Roslyn compiler converts C# to .NET managed assemblies (DLLs)
2. Managed code stripping reduces application size
3. All managed assemblies convert to standard C++ code
4. C++ compiler generates platform-specific machine code
5. Creates executables, DLLs, APK/AAB, or app bundles

Advantages:

• Improved runtime performance over Mono
• Shorter application startup times
• Supported across all platforms
• Supports managed code debugging identically to Mono

Disadvantages:

• Significantly longer build times than Mono
• Increased final application size
• Cross-compilation generally unsupported (must build on target OS)
• Exception: Linux cross-compilation supported from any desktop platform

Configuration:

• Player Settings: Edit > Project Settings > Player > Configuration > Scripting Backend
• Scripting API: PlayerSettings.SetScriptingBackend

Build Speed Optimization:

• Exclude project folders from antimalware scans
• Use fastest available storage drives
• Select "Optimize for code size and build time" (trades runtime performance)
• Use Burst compiler alongside IL2CPP for compatible code

Mono

• Faster build times (JIT compilation)
• Smaller build output
• Not available on all platforms (iOS requires IL2CPP)
• Less runtime performance than IL2CPP

When to Choose

Addressables Overview

The Addressable Asset System (com.unity.addressables v2.9.1) enables referencing assets by address rather than direct paths.

Key Concepts

• Mark any asset as "addressable" to generate a unique address callable from anywhere
• Supports loading from local or remote locations
• Uses asynchronous loading with automatic dependency resolution
• Replaces direct references, traditional asset bundles, and Resources folders
• Access via: Window > Asset Management > Addressables

Basic Usage Pattern

using UnityEngine;
using UnityEngine.AddressableAssets;
using UnityEngine.ResourceManagement.AsyncOperations;

public class AddressableLoader : MonoBehaviour
{
    [SerializeField] private AssetReference prefabRef;

    async void Start()
    {
        AsyncOperationHandle<GameObject> handle =
            Addressables.InstantiateAsync(prefabRef);
        await handle.Task;

        if (handle.Status == AsyncOperationStatus.Succeeded)
        {
            Debug.Log("Asset loaded successfully");
        }
    }

    void OnDestroy()
    {
        // Always release when done
        prefabRef.ReleaseAsset();
    }
}

Common Patterns

Platform-Specific Code

public class PlatformManager : MonoBehaviour
{
    void Start()
    {
        #if UNITY_IOS
        Application.targetFrameRate = 60;
        #elif UNITY_ANDROID
        Application.targetFrameRate = 60;
        Screen.sleepTimeout = SleepTimeout.NeverSleep;
        #elif UNITY_WEBGL
        // WebGL runs at browser refresh rate
        #elif UNITY_STANDALONE
        Application.targetFrameRate = -1; // Uncapped
        #endif
    }
}

Runtime Platform Check

void ConfigureForPlatform()
{
    switch (Application.platform)
    {
        case RuntimePlatform.IPhonePlayer:
            SetupMobileControls();
            break;
        case RuntimePlatform.Android:
            SetupMobileControls();
            break;
        case RuntimePlatform.WebGLPlayer:
            SetupWebControls();
            break;
        default:
            SetupDesktopControls();
            break;
    }
}

Build Profile Scripting

#if DEVELOPMENT_BUILD
    Debug.Log("Development build active");
#endif

#if ENABLE_IL2CPP
    // IL2CPP-specific code
#elif ENABLE_MONO
    // Mono-specific code
#endif

Anti-Patterns

1. Using Resources folder for everything instead of Addressables. Resources folder loads all assets at startup, increasing memory usage and load times.

1. Not using platform defines and relying solely on runtime checks. Compile-time defines exclude unused code from builds entirely.

1. String concatenation in WebGL loops. GC only runs at frame end in WebGL, causing massive temporary allocations. Use StringBuilder or NativeArray<T>.

1. Ignoring IL2CPP AOT restrictions. Reflection-heavy code, System.Reflection.Emit, and runtime code generation will fail under IL2CPP. Design with AOT in mind.

1. Shipping with Development Build enabled. Development builds include Profiler overhead and debug symbols, increasing size and reducing performance.

1. Not splitting APKs by architecture on Android. Shipping a single fat APK with both ARMv7 and ARM64 wastes user bandwidth. Use Split APKs or App Bundles.

1. Hardcoding platform paths. Use Application.persistentDataPath, Application.streamingAssetsPath, and Application.temporaryCachePath for cross-platform file access.

1. Not testing on actual devices. Android hardware varies enormously. Emulators and simulators do not represent real performance characteristics.

Key API Quick Reference

Related Skills

• unity-graphics — Rendering pipelines, shaders, and visual effects
• unity-packages-services — Package Manager workflow and Unity Gaming Services

Additional Resources

• Platform-Specific Development
• Build Profiles
• Scripting Symbol Reference
• iOS Development
• Android Development
• WebGL Development
• IL2CPP Scripting Backend
• Addressables Package
• Build Settings